New and established human neuroblastoma cell lines will serve as the basis for a multifaceted study of a unique human tumor. This neoplasm, which can be present at birth, is known to regress spontaneously and to differentiate into a benign tumor. The various investigations will attempt to determine the role an immune response plays in the development and regression of the tumor and mechanisms involved in cellular control. The fields of investigation include membrane glycoproteins, mouse-human cell hybrids, human genetics, tumor specific transplantation antigens, cellular and humoral immune responses and their correlation with prognosis and response to treatment.